Method of forming a ceramic matrix composite component, a ceramic matrix composite component and a tip member

ABSTRACT

A method of forming a ceramic matrix composite (CMC) component, a CMC component and a tip member are provided. The method of form the CMC component includes providing a component preform having a first end, a second end, and a cavity, the cavity having a pre-determined shape and a first engagement surface. The method includes forming a tip member from a pre-consolidated composite material, the tip member having a second engagement surface generally conforming to the first engagement surface. The method includes directing the second engagement surface to the first engagement surface. The method includes consolidating the component preform and tip member. The ceramic matrix composite component is formed having a desired geometry and the tip member stays in place in the cavity during operation of the ceramic matrix composite component.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

This invention was made with Government support under contract number DE-FC26-05NT42643 awarded by the Department of Energy. The Government has certain rights in the invention.

FIELD OF THE INVENTION

The present invention relates generally to gas turbines for power generation and, more specifically, to a method of forming ceramic matrix composite components, a ceramic matrix composite component and a tip member for gas turbines.

BACKGROUND OF THE INVENTION

Like turbine blades and vanes formed from more conventional superalloy materials, CMC blades and vanes usually include cavities and cooling passages to reduce weight, reduce centrifugal load, and reduce operating temperatures of the components. These features are typically formed in CMC components using a combination of removable and expendable tooling.

Forming CMC component with a cavity includes a number of steps, including using pre-forms. First, a plurality of ceramic plies, some of which can include reinforcing material or are pre-impregnated with matrix, are laid up on a mandrel or mold in a pre-determined pattern to provide desired final or near-net-shape and desired mechanical properties of component. The mandrel is generally selected from various polymers, or other meltable materials. The laid-up plies may be pre-impregnated (pre-preg) with matrix material, such as SiC or impregnated with matrix after lay-up of the plies. Prior to rigidization of the CMC pre-form, the mandrel is removed through a burn-out cycle. In the burn-out cycle, the mandrel forming materials, such as, various polymers, or other meltable materials are melted out or decomposed to gaseous products.

After the burn-out cycle, the CMC pre-form blade is very fragile due to burn-off of the volatile substances of the composite. The open tip area of the CMC pre-form requires capping or closing before use in gas turbines. In known processes, to close the open tip area of the CMC pre-form, a tip cap is inserted into the fragile open tip area. The tip cap can be formed from of a CMC laminate part having a number of plies, and shaped as the open tip area to fill the open tip area of the CMC pre-form. Forming the CMC laminate tip cap by cutting out the CMC plies to the desired shape and laying up the plies in the desired geometry is time and labor intensive. Challenges also arise with placing the CMC laminate having a number of plies into the open tip area. Additionally, because both the CMC laminate and pre-form blade are fragile prior to densification, these components can be easily damaged during assembly.

Therefore, a method of forming pre-form ceramic matrix composite cavity, a pre-form ceramic matrix composite cavity, and a method of forming ceramic matrix composite components that do not suffer from the above drawbacks is desirable in the art.

SUMMARY OF THE INVENTION

Certain embodiments commensurate in scope with the originally claimed invention are summarized below. These embodiments are not intended to limit the scope of the claimed invention, but rather these embodiments are intended only to provide a brief summary of possible forms of the invention. Indeed, the invention may encompass a variety of forms that may be similar to or different from the embodiments set forth below.

According to an exemplary embodiment of the present disclosure, a method of forming a ceramic matrix composite component is provided. The method includes providing a component preform having a first end, a second end, and a cavity, the cavity having a pre-determined shape and a first engagement surface. A tip member is formed from a pre-consolidated composite material, the tip member having a second engagement surface generally conforming to the first engagement surface. The second engagement surface is directed to the first engagement surface. The component preform and tip member are consolidated. The ceramic matrix composite component is formed having a desired geometry and the tip member stays in place in the cavity during operation of the ceramic matrix composite component.

According to another exemplary embodiment of the present disclosure, a ceramic matrix composite component is provided. The ceramic matrix composite component includes a component preform having a first end, a second end, and a cavity, the cavity having a pre-determined shape and a first engagement surface. The ceramic matrix composite component includes a tip member formed from a pre-consolidated composite material, the tip member having a second engagement surface generally conforming to the first engagement surface. The ceramic matrix composite component has a desired geometry and the tip member stays in place in the cavity during operation of the ceramic matrix composite component.

According to another exemplary embodiment of the present disclosure, a tip member for a cavity in a ceramic matrix composite component is provided. The tip member is formed from a pre-consolidated composite material. The tip member has a geometry substantially similar to a pre-determined shape of a cavity and a second engagement surface that cooperates with a first engagement surface of the cavity of the ceramic matrix composite component.

Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a ceramic matrix composite (CMC) component of the present disclosure.

FIG. 2 is a top schematic view of a pre-consolidated sheet including an outline of a tip member of the present disclosure.

FIG. 3 is a perspective view of a tip member of the present disclosure.

FIG. 4 is a perspective view of a component preform and tip member of the present disclosure.

FIG. 5 is a cross-sectional view along line 5-5 of FIG. 4 of the component preform and tip member of the present disclosure.

FIG. 6 is a cross-sectional view of FIG. 4 with first engagement surface and second engagement surface aligned of the present disclosure.

FIG. 7 is a flow chart of the method of forming a ceramic matrix composite component.

Wherever possible, the same reference numbers will be used throughout the drawings to represent the same parts.

DETAILED DESCRIPTION OF THE INVENTION

Provided is an economically viable method of forming a ceramic matrix composite (CMC) component, a CMC component, and a tip member that do not suffer from the drawbacks in the prior art. One advantage of an embodiment of the present disclosure includes a simpler method of forming tip members having a tapered cross section. Yet another advantage is a tip member that has a better fit tolerance within the ceramic matrix composite. Another advantage of an embodiment of the present disclosure includes a tip member that provides added mechanical load carrying capability compared to a vertically cut tip cap. Yet another advantage of the present embodiment is a lower cost in forming the tip member. Another advantage of the present embodiment is that there is a higher yield rate and easier reproducibility of tip members. Another advantage of an embodiment of the present disclosure includes a coated CMC article that limits the removal or loss of coating in the event of contact (e.g., tip rub) with another component in the system.

One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

Systems used to generate power include, but are not limited to, gas turbines, steam turbines, and other turbine assemblies such as land based aero-derivatives used for power generation. In certain applications, the power generation systems, including the turbomachinery therein (e.g., turbines, compressors, and pumps) and other machinery may include components that are exposed to challenging conditions. For example, certain power generation system components, such as blades, buckets, casings, rotor wheels, shafts, shrouds, nozzles, and so forth, may operate in high heat and high revolution environments. These components are manufactured using ceramic matrix composites and these components may also include cooling passages. The present disclosure provides a method to form ceramic matrix composite (CMC) components including cooling passages. An exemplary embodiment of the disclosure is shown in FIGS. 1-6 as a turbine blade, but the present disclosure is not limited to the illustrated structure.

FIG. 1 is a perspective view of a CMC component 100, such as, but not limited to, a turbine blade 120 or turbine vane. Turbine blade 120 is preferably formed of a ceramic matrix composite (CMC) material. Material for CMC component 100 includes, but is not limited to, an oxide based CMC, such as, but not limited to, alumina, mullite, boron nitride CMCs, boron carbide CMCs, sialons (silicon, aluminum, oxygen, and nitrogen) CMCs, intermetallic CMCs, and polymer based CMCs. Suitable examples of materials used to make CMC components 100, include, but are not limited to, SiC fibers impregnated with a SiC and carbon matrix with various binders. Turbine blade 120 includes an airfoil 122 against which the flow of hot exhaust gas is directed. Turbine blade 120 is mounted to a turbine disk (not shown) by a dovetail (not shown) which extends downwardly from airfoil 122 and engages a slot on the turbine disk. A platform 126 extends laterally outwardly from the area where airfoil 122 is joined to dovetail. Turbine blade 120 includes at least one cavity 490 as shown in FIG. 4, extending along the interior of airfoil 122. During operation of power generation system, a flow of cooling air is directed through cavity 490 to reduce the temperature of airfoil 122. Turbine blade 120 includes a pressure side 112 and a suction side 114 opposite pressure side 112. Turbine blade 120 includes a first end 116, the leading edge, and a second end 118, the trailing edge.

FIG. 2 is a top schematic view of a pre-consolidated sheet 210 including an outline 212 of a tip member 200. Pre-consolidated sheet 210 comprises a plurality of pre-preg ceramic unidirectional plies already aligned and ready to be cut. In one embodiment, pre-consolidated sheet 210 comprises pre-preg plies including epoxy/polymer based resins with carbon, fiberglass, and/or KEVLAR® fibers. In another embodiment, pre-consolidated sheet 210 comprises pre-preg plies including SiC fibers impregnated with a SiC and carbon matrix with various binders. In one embodiment, pre-consolidated sheet 210 has a thickness of about 0.254 millimeters (10 mils) to about 1 centimeter (394 mils), or alternatively about 0.5 millimeters to about 90 millimeters, or alternatively from about 1 millimeter to about 80 millimeters. As depicted in FIG. 2, a cut-out or outline 212 of tip member 200 is shown in pre-consolidated sheet 210. Suitable method used to cut out tip member 200 from pre-consolidated sheet 210, include, but are not limited to, cutting, laser cutting, ultrasonic cutting, and waterjet cutting.

FIG. 3 illustrates tip member 200 cut from pre-consolidated sheet 210. Tip member 200 includes a first end 314, trailing edge, a second end 316, leading edge, a top 304, a bottom 306 and second engagement surface 302. Second engagement surface 302 includes a tapered surface 310. Second engagement surface 302 including tapered surface 310 cooperate with first engagement surface 594 of component preform 400 (see FIG. 4). Geometry of tip member 200 is substantially similar to blade tip 430 of component preform 400. As shown in FIG. 4, first end 314 of tip member 200 is inserted into cavity 490 of component preform 400. In one embodiment, depending on size of and shape of cavity 490 of component preform 400 about half of tip member 200 is inserted into cavity 490.

As shown in the cross-section view of FIG. 5, tip member 200 is rotated, as shown by arrow 500, to allow second engagement surface 302 of tip member 200 to engage with first engagement surface 594 of preform component 400, such that top 304 of tip member 200 is flush with end of blade tip 430 of preform component 400. In one embodiment, second engagement surface 302 includes taper 310 generally conforming to taper 596 of first engagement surface 594. In one embodiment, taper 596 of first engagement surface 594 is wider at the bottom, as shown in FIG. 5. In one embodiment, as depicted in FIG. 5, tip member 200 has a reverse taper 310 that cooperates with taper 596 of first engagement surface 594. In an alternative embodiment, taper 596 of first engagement surface 594 is narrower at the bottom.

FIG. 6 depicts the tip member 200 situated within cavity 490 of component preform 400 with first engagement surface 594 and second engagement surface 302 being adjacent. Taper 310 of tip member 200 cooperates with taper 596 of component preform 400 to secure tip member 200 in cavity 490.

FIG. 7 is a flow chart describing method 700 of forming ceramic matrix composite component 100. Method 700 includes providing component preform 400 having first end 402, second end 404, and cavity 490 (see FIG. 4), step 701. As shown in FIG. 4, cavity 490 has a pre-determined shape and first engagement surface 594. Method 700 includes forming tip member 200 from pre-consolidated composite material 210 (see FIGS. 2 and 3), step 703. Tip member 200 has second engagement surface 302 generally conforming to first engagement surface 594 of component preform 400 (see FIGS. 5 and 6). Method 700 includes directing second engagement surface 302 to first engagement surface 594 (see FIGS. 5 and 6), step 705. Step of directing, step 705, generally includes placing first end 402 of tip member 200 in opening 592 of cavity 490 of component preform 400 with second end 316 of tip member 200 being above or outside cavity 490 (see FIGS. 4-5). Step of directing, step 705, includes rotating or flipping tip member 200, as shown by arrow labeled 500, such that first end 314 of tip member 200 engages with first end 402 of component preform 400 and second end 316 of tip member 200 engages with second end 404 of component preform 400 resulting in second engagement surface 302 engaging with first engagement surface 594. Method 700 includes consolidating component preform 400 and tip member 200, step 707. The step of consolidating, step 707, includes any suitable composite processing methods, such as, but not limited to, melt infiltration, bonding, brazing, chemical vapor infiltration, polymer impregnation and pyrolysis, and other known composite processing methods. Method 700 provides ceramic matrix composite component 100 having a desired geometry and with tip member 200 that stays in place in cavity 490 during operation of ceramic matrix composite component 100.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. 

What is claimed is:
 1. A method of forming a ceramic matrix composite component comprising: providing a component preform having a first end, a second end, and a cavity, the cavity having a pre-determined shape and a first engagement surface; forming a tip member from a pre-consolidated composite material, the tip member having a second engagement surface generally conforming to the first engagement surface; directing the second engagement surface to the first engagement surface; and consolidating the component preform and tip member; wherein the ceramic matrix composite component is formed having a desired geometry and the tip member stays in place in the cavity during operation of the ceramic matrix composite component.
 2. The method of claim 1, wherein the ceramic matrix composite component is a component selected from the group consisting of turbine blades, turbine nozzles, turbine buckets, and combinations thereof.
 3. The method of claim 1, wherein the pre-consolidated composite material comprises ceramic unidirectional plies, organic or inorganic based pre-preg plies, or organic or inorganic based cross-plies.
 4. The method of claim 1, wherein the pre-consolidated composite material has a thickness of about 0.254 millimeters to about 1 centimeter.
 5. The method of claim 1, wherein the step of forming includes cutting, laser cutting, waterjet cutting, and combinations thereof.
 6. The method of claim 1, wherein the first engagement surface includes a taper.
 7. The method of claim 1, wherein the taper of the first engagement surface forms a geometry that narrows toward an end of the cavity.
 8. The method of claim 6, wherein the second engagement surface includes a taper generally conforming to the taper of the first engagement surface.
 9. A ceramic matrix composite component comprising: a component preform having a first end, a second end, and a cavity, the cavity having a pre-determined shape and a first engagement surface; a tip member formed from a pre-consolidated composite material, the tip member having a second engagement surface generally conforming to the first engagement surface; and wherein the ceramic matrix composite component has a desired geometry and the tip member stays in place in the cavity during operation of the ceramic matrix composite component.
 10. The ceramic matrix composite of claim 9, wherein the ceramic matrix composite component is a component selected from the group consisting of turbine blades, turbine nozzles, turbine buckets, and combinations thereof.
 11. The ceramic matrix composite of claim 9, wherein the pre-consolidated composite material has a thickness of about 0.254 millimeters to about 6.35 millimeters.
 12. The ceramic matrix composite of claim 9, wherein the step of forming includes cutting, laser cutting, waterjet cutting, and combinations thereof.
 13. The ceramic matrix composite of claim 9, wherein the first engagement surface includes a taper.
 14. The ceramic matrix composite of claim 13, wherein the taper of the first engagement forms a geometry that narrows toward an end of the cavity.
 15. The ceramic matrix composite of claim 9, the second engagement surface of the tip member includes a taper generally conforming to the taper of the first engagement surface.
 16. A tip member for a cavity in a ceramic matrix composite component, the tip member formed from a pre-consolidated composite material, the tip member having a geometry that conforms to a pre-determined shape of a cavity and a second engagement surface that cooperates with a first engagement surface of the cavity of the ceramic matrix composite component.
 17. The tip member of claim 16, wherein the first engagement surface includes a taper.
 18. The tip member of claim 16, wherein the second engagement surface of the tip member includes a taper generally conforming to the taper of the first engagement surface. 